328 Plums and Plum Culture 



caused by a fungus, known to science as Cladosporium 

 carpophilum. 



No definite experiments seem to have been made 

 in the control of this scab except by Chester, who 

 worked upon peaches.* He reports that early and re- 

 peated sprayings with bordeaux mixture are effective. 

 Craig has also reported success in the use of bordeaux 

 mixture. Jt seems probable that the general prophy- 

 lactic treatment with bordeaux mixture recommended 

 repeatedly in this chapter will overcome this disease in 

 common with nearly all the others of fungous origin 

 which attack the plum. 



Leaf rust. — The leaf rust of the plum appears to 

 have received little notice from horticulturists, and the 

 mycologists have paid small attention to it except to 

 place it in their lists. Hedrick thought it to be of 

 economic importance in Oregon,! and Pierce made 

 experiments in its treatment on the Pacific coast. The 

 present writer has observed it in great abundance on 

 several species of wild plums and on some cultivated 

 varieties in Oklahoma. In that country it seems to be 

 especially virulent, and, apparently, may easily come to 

 be of practical consequence. The rust appears on the 

 leaves, usually on the under sides, late in the summer. 



Fairchild t recommends bordeaux mixture for this 

 disease. Pierce § secured good results from the use of 

 an ammoniacal copper carbonate solution; but it is 

 probable that the bordeaux mixture would have done 

 at least as well. It seems fair to expect that the care- 

 ful use of bordeaux mixture during the early part of 



*F. D. Chester, Delaware Experiment station Report (1896), 

 pages 60-63. 



tU. P. Hedrick, Oregon Experiment station Bulletin 45:67. 1897. 



$D. G. Fairchild, Bordeaux Mixture as a Fungicide, United States 

 Department of Agriculture, Division Vegetable Pathology, Bulletin 6. 



§N. B. Pierce, Journal of Mycology, 7:354-363. 1894. This is the 

 fullest account of the plum rust extant. 



